1. Field of the Invention
This invention relates to construction of a door frame in a motor vehicle door, and more particularly to improvements in construction of a door frame, wherein a plate member is continuously bent to form two channels contiguous to each other.
2. Description of the Related Art
As shown in FIG. 3 for example, there has heretofore been a door frame F comprising a first channel 2 for holding a door weather strip, not shown, and a second channel 4 contiguous to the first channel 2 on the outboard side, for holding a door glass run, not shown, wherein the first and the second channels 2 and 4 are formed by continuously bending a plate member, a bottom portion 6 of the first channel 2 is of double-ply structure and the rear surface thereof is directed toward a compartment 8 and the second channel 4 is formed by a pair of bent extensions 3A and 3B which are bent and extended in two direction separating from each other from the outer end position of the bottom portion 6 of double-ply structure.
In FIG. 3 designated at 5 is a third channel for holding a sub-door weather strip, not shown.
In the conventional construction of the door frame as shown in FIG. 3, plate sections 6A and 6B constituting the bottom portion 6 are welded to each other by spot weldings at suitable intervals in the longitudinal direction thereof.
Furthermore, a bottom portion 5A of the third channel 5 and a side wall 4A superposed on the bottom portion 5A are also spot-welded together in a superposed state.
In this case, the sub-door weather strip is mounted to the third channel 5 and the glass run is mounted to the second channel 4, so that the spot-weld marks for welding the bottom portion 5A to the side wall 4A is concealed.
However, spot-weld marks 9 at the bottom portion 6 of the first channel 2 are exposed to the compartment's side.
As a result, the mark portions, which are identified by the reference numeral 9, should be repaired to trim the surfaces.
Furthermore, since the bottom portion 6 is spot-welded at the center position along the widthwise direction, the upper half portion of the bottom portion 6 has a low resisting force against separating the plate sections 6A and 6B from the side of the second channel 4.